Automated Meter Reading (AMR) started out as a more efficient and accurate method for utility metering data collection, compared to manual meter reading of electric, gas and water meters. Several important advantages of AMR over manual meter reading helped develop it into a specialized branch of the data communications and telemetry industry. Worth noting among these advantages are the reliability, accuracy and regular availability of metering data, collected from hard-to-reach meter locations as well as from standard meter locations; higher customer security (no need to enter homes) and satisfaction (accurate bills); and reduced cost of customer service call center and service house calls for settling billing disputes.
Various technologies are implemented in AMR. All implementations perform the tasks of interfacing the meter in order to sense consumption, communicating consumption data to a central site and storing consumption data in a computer system at the central site. Wireless technologies have be. the most common in AMR system implementation due to the ease of the installation process and, in many cases, the low initial and operating costs of the system.
Among wireless implementations of AMR, a categorization has been established between mobile data collection systems and fixed-base data collection systems, or networks. Fixed network systems have some important distinctive advantages, brought about by the frequent (typically at least daily) consumption data collection, in comparison with mobile systems, which merely provide a more reliable method of collecting monthly meter reads for billing purposes. Worth noting among these advantages are: flexibility of billing date; marketing tools such as time-of-use (TOU) rates, demand analysis and load profiling, which enable clearer market segmentation and more accurate forecasts for utility resource generation, and also serve the goal of energy conservation and efficient consumption; and maintenance tools such as immediate notification of utility resource leakage or of account delinquency. These advantages have triggered increased interest and commercial activity regarding fixed network data collection systems for utilities, particularly utilities in regions undergoing deregulation of utility services.
Several methods and systems for implementing fixed-base data collection from a plurality of remote devices, such as utility meters, to a central location, have been developed and introduced in the past years. A categorization has evolved as the AMR industry developed, generally differentiating between one-way and two-way wireless data networks. Some systems, such as those described in U.S. Pat. No. 5,438,329 to Gastouniotis et al., U.S. Pat. No. 5,883,886 to Eaton et al. and U.S. Pat. No. 6,246,677 to Nap et al., require that each meter module on the network be a two-way module, i.e. contain a receiver circuit in the meter module. Although two-way communication features such as on-demand meter reading and other remote commands for meter configuration and control are generally desirable, they may not be required for the entire meter population of a utility. Since the inclusion of a receiver in the meter module contributes significant cost to the module, it would be most desirable to allow a utility service company the flexibility to deploy an AMR network, which may contain and support both one-way and two-way meter modules.
U.S. Pat. No. 5,963,146 and No. 6,172,616 to Johnson et al., assigned to Itron, Inc. of Spokane, Wash. (referred to henceforth as the Itron network) and U.S. Pat. No. 6,163,276 to Irving et al. and U.S. Pat. No. 6,195,018 to Ragle et al. (referred to henceforth as the CellNet network) describe data collection networks that may also operate as one-way (collection only) data networks. These networks support the large volume of data, expected by advanced metering applications, by deploying intermediate data collection nodes (Remote Cell Nodes, or RCN's, in Itron's network and Microcell Controllers in CellNet's network), each of which creates a small data collection cell with a short-range RF link and a typical service population of several hundreds of meters. In these networks, the data collection nodes receive messages from meter modules, perform metering data analysis and extract, or generate, specific meter function values to be transmitted to the next level in the network hierarchy. The wide-area network connecting the intermediate level and the higher level is typically a wireless network operating on an additional, licensed, RF channel, in order to avoid interference. This configuration, which distributes the ‘network intelligence’ among many data collection nodes, serves the purpose of reducing the data flow into the central database when a large amount of meters is analyzed for load profile or interval consumption data. It also serves the purpose of reducing air-message traffic between the intermediate node and the higher-level concentrator node, referred to as IDT (Intermediate Data Terminal) in the Itron network and Cellmaster in the CellNet network.
However, the configuration of the Itron and CellNet networks becomes inefficient in the common case where only a part, or none, of the meter population requires advanced metering services like TOU rates, while basic daily metering service is required for the whole meter population. This inefficiency is imposed by the short-range radio link between the meters and the data collection nodes, which significantly limits the number of meters a node can serve, regardless of how many meters require or do not require to be read frequently for interval consumption data. That way, an expensive infrastructure of up to thousands of data collection nodes may be deployed, which may often consist of plenty of unused excess capacity. A more efficient network would therefore be desirable, in order to reduce basic equipment cost, as well as installation and ongoing maintenance costs.
In addition, because of the large number of data collection nodes, the most cost-efficient means for the WAN layer in these multi-tier networks would be a wireless WAN. However, to avoid interference from meter modules, as well as over-complication of the data protocols, a licensed frequency channel is typically used for the WAN, adding to the overall cost of services to the network operator. A network composed of only one wireless data collection layer would therefore be desirable, particularly if operating in the unlicensed Industrial, Scientific and Medical (ISM) band.
Yet another disadvantage of networks with distributed intelligence among the data collection nodes is the limited storage and processing power of the data collection nodes. A system that could efficiently transfer all the raw data from the meter modules to the network's central database would therefore be desirable, since it would allow for more backup and archiving options and also for more complex function calculations on the raw meter data.
The Itron patents also quote a previously developed system by Data Beam. This data collection network included few reception sites, each one capable of handling up to tens of thousands of meters. In order to allow for long communication range, the meter module antenna was installed in a separate (higher and/or out of building) location from the meter module, creating significant additional cost to the meter module installation, thus significantly reducing the commercial feasibility for practical deployment of the network. In addition, the meter module's power consumption requirements required a mains power source or expensive batteries, further reducing the network's commercial feasibility.
None of the above-mentioned systems of the prior art offers a sufficient level of flexibility, enabling the network operator to deploy a reliable, low cost, fixed data collection network, while adjusting its initial and ongoing costs to a wide range of application requirements, from basic daily meter reads to full two-way capabilities. Inefficiencies exist in each two-way network, in which the two-way capability is imposed on the entire meter population, and also in each one-way network, in which small cell configuration requires a large, unnecessary investment in infrastructure.
It is therefore desirable to introduce a simple to deploy, but highly scalable, modular and reliable data collection system, which would offer a wide range of service options, from basic metering to advanced applications based on interval consumption data, to full two-way applications, while keeping the system's deployment and ongoing costs proportional to the service options and capacity requirements selected for various segments of the meter population.